1. Field of the Invention
This invention relates to a cap removing apparatus employed when, for example, a cap blocking an opening of a test tube is removed from the test tube and, more particularly, to a structure to correct a posture of a knob portion provided on an outer peripheral edge of the cap to a regular posture and automatically remove the cap from the opening of the test tube by grasping the knob portion.
2. Description of the Related Art
For example, an opening of a test tube containing a sample such as blood is blocked by a cap. The cap is produced of a soft material such as synthetic resin and has a flange-like knob portion on an outer peripheral edge thereof. To remove this kind of cap from a test tube, the cap has been detached from an opening of the test tube by grasping the knob portion by fingertips. However, removing caps one by one from respective test tubes by manual work has spent much time and the operability has been poor.
Thus, a removing apparatus for automatically removing a cap from an opening of a test tube has been developed. Japanese Patent No. 2731729 discloses such a removing apparatus. The publicly known removing apparatus comprises a holder which holds a test tube in an upright posture, a transport path having a belt conveyor which transports the test tube held by the holder together with the holder, a rotation mechanism provided in the transport path to rotate the test tube about a central longitudinal axis thereof, a correction mechanism which corrects a posture of a knob portion of a cap when the test tube is rotated by the rotation mechanism, and a removing mechanism which removes the cap from the test tube by grasping the knob portion having the posture corrected by the correction mechanism.
The transport path of the removing apparatus has a correcting position and a removing position at its middle part. The correcting position and the removing position are separated from each other in a transporting direction of the test tube. The rotation mechanism and the correction mechanism are provided at the correcting position. The removing mechanism is provided at the removing position.
The test tube transported in the transport path is fed to the removing position via the belt conveyor after the posture and direction of the knob portion of the cap are corrected at the correcting position. The cap is removed from the opening of the test tube by the removing mechanism, at the removing position.
In the conventional removing apparatus, however, since the correction mechanism and the removing mechanism are separated from each other in the transporting direction of the test tube, the transport path is long. As a result, a large space to provide the transport path is required and the removing apparatus cannot be made compact.
Moreover, transmission of vibration from the belt conveyor to the test tube cannot be prevented during a process in which the test tube is transported from the correcting position to the removing position. Thus, the test tube is rotated little by little about a central longitudinal axis thereof and the direction of the knob portion corrected at the correcting position is changed. As a result, even if the test tube is fed to the removing position, the knob portion of the cap cannot be grasped by the removing mechanism. Therefore, the cap cannot be removed from the test tube or the operation of removing the cap cannot be automated.
In addition, the test tube is transported from the correcting position to the removing position every time the cap is removed from the test tube, in the conventional removing apparatus. For this reason, much time must be spent after correcting the knob portion of the cap and before removing the cap.